SIMBAD references

A complete period variation analysis and new light curves of V 839 Oph together with new ephemeris data are presented. The period variation was found to be dP/dt=3.1x10^–7d/yr. The period increment indicates that the conservative mass transfer rate from the less massive component to the more massive one is 6.5x10^–7M_☉/yr. We fitted parabolic and we discuss the possible detection of sinusoidal curves to the (O-C) diagram and sinusoidal oscillations with period of about 20yr and semi-amplitude of 0.0065 day. A simultaneous solution of the B and V light curves was computed using the Wilson-Devinney synthetic light-curve code. The light curve solution indicates that the A-type W UMa-type system is in contact with a filling factor of ∼39%.